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Show 392 MR. E. A. SMITH ON SHELLS FROM ADEN. [June 16, recognize the differences which distinguish it. It is a trifle and higher than the Mediterranean form, but chiefly differs in the sculpture. The cancellation is coarser, the radiating ribs are peculiarly and closely imbricately squamate and thicker, and the filled-up portion of the slit is less prominent. These may be regarded by some people as varietal characters, but in answer to this I would remark that if we unite as one species forms from different seas as distinct as those from the Mediterranean and Red Sea, we should be compelled to include others also, such as E. micans, A. Ad., from Torres Straits, and E. Candida, A. Ad., from Adelaide, both of which have certain points of resemblance to E. elongata and to each other, but which still are fairly recognizable as distinct species. 3. CHITON SICULUS, Gray. (= C. affinis, Issel.) C. affinis, Issel, may be regarded as a strongly marked form of the Mediterranean species. There is also a species found in New Zealand, C. siculoides, Cpr. MSS. = C. cereus, Reeve, which is also inseparable. C. muricatus, A. Adarns, from Sydney, and C. stanyeri, Reeve, = C. insculptus, A. Ad., from New Zealand, are likewise very similar. 4. CHITON (ACANTHOCHITES) DISCREPANS, Brown. I cannot separate C. scutiger, Ad. & Reeve., Corean Archipelago, and C. carinatus, A. Ad. & Angas, from Port Jackson, from this species. 5. VoLVULA ACUMINATA (Brug.). The two specimens obtained by Mr. MacAndrew are more slender than this species and agree in form with V. angustata, A. Adams, from the Philippine Islands, and V. cylindrica, Smith, from Whydah, West Africa, which apparently is the same species. 6. PHILINE APERTA (L.). P. orientalis, A. Adams, and P. angasi, Crosse, both Australian, are inseparable from this species, which also occurs at Natal (Cooke). 7* (LEUCONIA DENTICULATA, Mont.) Not considered. 8. PECTEN VARIUS, Linn. Mr. MacAndrew collected three specimens which he considered belonged to this species. Of these Mr. Cooke x informs us that one is undoubtedly a worn shell of P. senatorius, Gmel. This I fully 1 Ann. Mag. Nat. Hist. 1886, vol. xvh. p. 134. |